Getting to know your Potting Containers: When a container isn't just a container
When choosing a container for your potted plants there's lots of things to consider. I often find myself making selections based on what I already have in my yard that I can reuse and what will be big enough to for my plant, but there's more to it than that. Container material adds another layer to your yards microclimates and it's something you can use to your advantage to fine tune finding just the right spot/microclimate in your yard. Alternatively, if you are planting in what you have and what you find, (which is what I often do), then knowing the different considerations to make regarding your containers material will help keep your plants happy and healthy.
Brown/Light Colored Plastic:
Benefits: Inexpensive; lightweight; comes in many sizes and shapes; cooler than darker colored pots; usually keeps vertebrate pests out of bottom of pot
Challenges: Cooler than black pots (so that's a benefit, unless you live in a cooler area, or in the winter, and the difference is minimal); not recyclable in most cities, so if they break or when they get old they need to go in the trash if they can't be upcycled for another garden purpose; don't usually provide much insulation or heat protection for new transplants, sensitive plants, or smaller plants
How to use it to increase your microclimates: Overall, great for plants that you might want to move around since they are lightweight; can be reused for many years; great for annual plants that you want to dump and refresh the soil each year/season since they pot itself doesn't add much weight; great for plants that you are worried about getting water logged (as long as they have a drain hole, which is a must!) since the pot itself doesn't retain any water….that also means you need to watch that they don't dry out more often then plants in ground or in other types of pots.
Black/Dark Colored Plastic:
Benefits: Many of the same benefits as above, but can also add that black pots tend to absorb heat and might be good for plants (esp in the cooler seasons) that need a little more warmth, or like warm roots
Challenges: Many of the same drawbacks as the pots above, but will absorb more heat than lighter colored pots so it's important to keep an eye on that during warmer weather
How to use it to increase your microclimates: Again, same benefits as light colored pots, but also can be used to keep plants a little warmer if that is something they benefit from.
Note: The descriptions above fit most pots that you buy plants and trees in at the garden center, but note that those pots are often much thinner than the brown or light colored pots you would buy at the store for planting. The pots' thin plastic doesn't provide much insulation from heat or cold and plants in these pots tend to dry out very quickly. These pots are also not usually recyclable but could be used to start seeds, or could be donated to friends, family, or to a community garden near you that might want to start their own seeds or cuttings.
Wood (sealed gaps/not sealed): If you are thinking about making your own planters, containers, you want to think about the type of wood you are using (treated or not for example) with what type of crops. For ornamental plants that you are not eating it is less crucial that you use untreated wood, but the chemicals in treated wood still might be an area of concern with regards to overall soil contamination (even if it is in small amounts)
Benefits: Nice, natural look; biodegradable; wood absorbs some heat/cool and helps buffer soil temperature; Wood will absorb water and that can help buffer temperature of soil and soil moisture. Some wood pots have their seams and insides sealed and some don't. This will impact how much water is absorbed and how much water leaks out as you water. Note this when getting to know your soil in these types of pots.
Challenges: Often more expensive that plastic pots; can be pretty heavy depending on size and if it's able to absorb water (sealed vs unsealed); biodegradable is also a potential down side, especially if you use it for a perennial plants since pot material will break down over time (some will last for a few seasons, some for many, many years depending on wood type); bottoms will often rot out sooner than sides and burrowing pests like gophers can get into them
How to use it to increase your microclimates: Great foundational pots for your garden if you get bigger ones (like half wine/whisky barrels) or smaller containers can be moved around. Wood can buffer soil temperature and also help keep moisture in. Wooden pots can also absorb water from soil, so whether the pots are sealed or lined will make a difference on that, and you need to get to know how this pot interacts with your soil and plants that you choose for these pots
Glazed ceramic:
Benefits: Nice looking pots that often add color and beauty to the garden! Glazed ceramic pots are one of the more expensive options and if you're on a budget, but would like to incorporate this type of pot into your garden, consider using just a few (or even one) to add a pop of color! Can also buffer soil temperatures in cooler areas or times of year; keeps vertebrate pests out of bottom of pot
Challenges: These pots present lots of challenges in San Bernardino County in warmer weather absorbing a lot of heat during warmer months; don't absorb water because the ceramic is sealed, but that also means that they get water logged more easily; many plants that are more herbaceous/tender that will struggle with the radiating heat off this type of pot; these pots are often heavy compared to unglazed ceramic pots.
How to use it to increase your microclimates: Great for a pop of color for your garden! These pots do well with succulents and other plants that can tolerate the radiating heat in the summer. Plants that are more tolerant (or you are willing to carefully water, checking before watering) of some standing water are good choices for these pots.
Metal containers/beds with bottoms: Note that many metal planter beds and containers are insulated with straw or other material to protect plants from over heating on hot days when the metal gets hot. Any liner or insulation you add will have an impact (sometimes negative, sometimes positive) on water absorption, amount of soil you can add, and more, so it's important to do a little research and be observant, looking for plant health issues, or at how quickly the soil dries out.
Benefits: Vertebrate pests will not be able to get through material to get into container (although they still can go over the sides); depending on any insulation you use this might help with buffering soil temperatures, but if soil is in contact with metal temperatures in the soil will fluctuate with outside hot and cold temperatures
Challenges: Metal will get very hot in the summer (and can get very cold in summer); can be challenging to add more drain holes if needed; can be heavy depending on size
How to use it to increase your microclimates: These containers are often used when gardening on cement or other hard surfaces, or areas where planters may be temporary; also useful in areas with lots of gophers or other burrowing vertebrate pests.
Upcycled containers: these can vary widely depending on what type of material you are using and upcycling
Benefits: great to reuse containers, and can end up with lots of creative “yard art”
Challenges: must keep in mind what type of plants you are planting (edible or not) and what materials the upcycled containers are made of, so that you are not exposing yourself to any undesirable chemicals; when in doubt reach out to our Master Gardeners helpline (By phone:(909)387-2182
By email: mgsanbern@ucanr.edu) to find out more about the type of container you would like to use!
Lastly, it's important to have drain holes in your pots to keep plants from sitting in standing water. You might need to add drain holes or adjust your watering accordingly to keep plants healthy. A variety of pots in your yard are a great way to get benefits from all these different container types or using one type in your yard will help you keep some things in your garden more constant!